Component feeder configuration monitoring

ABSTRACT

A system and method for monitoring the configuration of component feeders in a placement machine having a series of feeder slots for holding the component feeders. The system includes slot markers for installation on the placement machine to correspond to the feeder slots, feeder markers for installation on the component feeders of the placement machine, and a marker detector (e.g., a bar code scanner) adapted to monitor the arrangement of slot markers and feeder markers in the machine while the machine is in operation.

BACKGROUND OF THE INVENTION

This invention relates to monitoring the configuration of componentfeeders on a component placement machine.

Component placement is one of the most labor and data intensiveoperations in electronic board assembly. Current high speed componentplacement equipment can place up to 10,000 to 30,000 components perhour, depending on configuration, and can carry up to 1,000,000 or moreindividual components.

Surface mount components are typically supplied by component vendors asrolled tapes of components that must be loaded onto individual feeders,sometimes called component dispensing cartridges, that can then bemounted in corresponding feeder slots on the machine. These rolls ofcomponents (up to, in some cases, 10,000 or more components per roll)may be loaded onto the feeders either at a stock room or at the machine,and the loaded feeders then loaded into feeder slots.

Component placement machines can have many feeder slots (e.g., 150 ormore), each accessible by a placement turret or other picking mechanismthat picks individual components from the feeders in the slots andplaces them in particular locations on a printed circuit board,according to programmed instructions. For application flexibility, eachfeeder and slot is generally constructed to be compatible with manydifferent components.

The physical arrangement of components, feeders and slots must be inaccordance with the expected arrangement as programmed in the machine.Any error in the arrangement can cause a corresponding error in theplacement of components on the board. In a high volume, low mixmanufacturing environment, a component loading error can produce a highnumber of defective printed circuit boards in a short period of time. Ina low volume, high mix environment the chance of component loading errorincreases because of frequent feeder manipulation for product changeover.

To help eliminate loading errors, some have suggested placing bar codelabels on individual feeders and slots and then scanning the feeder andslot labels with a hand-held scanner as the feeders are placed in theslots (i.e., before the machine begins its operation).

SUMMARY OF THE INVENTION

The invention features a system for guarding against some of the typicalloading errors that can occur even with the most conscientious machineoperators, as well as providing much-needed inventory and maintenancedata.

According to one aspect of the invention, a apparatus for monitoring theconfiguration of component feeders is provided, for use in a placementmachine having a series of feeder slots for holding the componentfeeders. The apparatus includes slot markers for installation on theplacement machine to correspond to the feeder slots, feeder markers forinstallation on the component feeders of the placement machine, and amarker detector adapted to monitor the arrangement of slot markers andfeeder markers in the machine while the machine is in operation.

The slot markers and feeder markers may be light-scannable labels, themarker detector including a scanner arranged to scan the slot markersand feeder markers.

Preferably, the marker detector is arranged to substantiallysimultaneously scan the slot marker of a given slot and the feedermarker of the feeder in (i.e., installed in) the given slot. Theapparatus can be triggered to scan a given slot marker and correspondingfeeder marker by the machine as the machine picks a component from theslot corresponding to the given slot marker. By "substantiallysimultaneously" we mean within the same pick cycle.

The marker detector, in some embodiments, is adapted to compare thearrangement of slot markers and feeder markers to stored data while themachine is placing components. The apparatus preferably also includesmeans to alert an operator (e.g., an audible or visible alarm) upondetection of an undesirable arrangement of slot markers and feedermarkers.

The apparatus may be adapted to work with different types of placementmachines. For example, for use with a placement machine that includes amoving picking mechanism and a stationary feeder platform, the scanneris preferably constructed to be attached to the moving picking mechanismof the placement machine. For use with a placement machine that includesa rotatable picking mechanism, a moving feeder platform and a stationaryportion, the scanner is preferably constructed to be attached to thestationary portion of the placement machine.

The apparatus includes, in preferred embodiments, a data storage deviceadapted to store component feeder configuration data. The data storagedevice may be adapted to record the number of components remaining ineach component feeder, and/or to track the number of times a givencomponent feeder has been accessed by the placement machine.

The apparatus may also be adapted for use with multiple placementmachines. In such configurations, the apparatus should include a datalink between the multiple placement machines and the data storagedevice, preferably such that the data storage device may be constructedto update component feeder information from the multiplicity ofplacement machines.

The apparatus may be configured for use with component reels withlight-scannable labels, also including a loading scanner adapted to scanthe reel labels and feeder labels as the reels are mounted upon thefeeders to identify which component is loaded on a given feeder.

The apparatus is particularly well suited for use in placement machinesfor mounting electronic components on circuit boards. Such machinesgenerally have a series of feeder slots for holding component feeders,and a picking device constructed to pick components from the feederslots for mounting to a circuit board.

According to another aspect of the invention, a package of electroniccomponents includes a housing adapted to be inserted into a componentfeeder of a placement machine, a multiplicity of electronic componentscontained within the housing and arranged to be sequentially picked fromthe package by the placement machine, and a removable label affixed tothe package. The removable label has an adhesive backing for remountingthe label, after removal from the package, on a component feeder, andlight-scannable information printed thereon for identifying thecomponents of the package. Preferably, the package has a multiplicity ofsuch removable labels, for multiple remountings of the package ondifferent feeders.

According to another aspect of the invention, a method for monitoringthe configuration of component feeders in a placement machine having aseries of feeder slots for holding the component feeders is provided.The method includes scanning, while the machine is in process of pickinga component from a given feeder slot, a slot marker corresponding to thegiven slot and a feeder marker corresponding to the component feeder inthe given slot. The method also includes comparing configurationinformation gathered by the scanning with stored information to checkfor configuration errors.

Preferably, the steps of scanning and comparing are performed while themachine is placing components.

In some embodiments, the method also includes alerting an operator upondetection of an undesirable arrangement of slot markers and feedermarkers.

Prior to the operation of the placement machine, the method may alsoinclude installing component reels in feeders, scanning reel labels andfeeder labels of their associated feeders to identify which componentsare loaded on which feeders, and mounting the loaded feeders on theplacement machine.

The invention can reduce the chance of component loading error bycontinuously checking the arrangement of component feeders on aplacement machine and alerting the operator before a mistaken componentis placed. Advantageously, the system does not require the machine tosit idle while component arrangement is checked. In addition, theinvention can provide accurate component inventory information and trackindividual feeder use for maintenance purposes. The basic components ofthe system are readily installed on conventional placement machines.

Other features and advantages will also be apparent from the followingdescription and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of a first type of componentplacement machine.

FIG. 2 illustrates loading a component feeder.

FIG. 3 is a schematic illustration of a feeder configuration monitoringsystem according to the invention.

FIG. 4 is a flow diagram of the basic operation of the system of FIG. 3.

FIG. 5 illustrates a system with several machine monitors and a commondatabase.

FIG. 6 is a flow diagram partially detailing the memory management ofone of the machine monitors in the system of FIG. 5.

FIG. 7 is a schematic illustration of a second type of componentplacement machine.

FIG. 8 is an example of a feeder bar code label.

FIG. 9 shows a component reel with removable labels.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 illustrates the basic components of a component placement machine10 for mounting electronic components (e.g., surface mount components)on printed circuit boards and the like. In the configurationillustrated, a rotatable turret 12 has several pick-place mechanisms 14located about its periphery. Each pick mechanism 14 is configured topick individual components from selected feeders 16 mounted on a movablefeeder platform 18 on one side of turret 12 and to place the pickedcomponents in predetermined positions on a printed circuit board 20 onthe other side of the turret. Feeder platform 18 moves back and forth(along the feeder platform) to present the desired feeder 16 topick/place mechanisms 14, and can typically hold between about 70 and150 feeders.

Before mounting feeders 16 in their respective slots on feeder platform18, they are loaded with reels 20 of components as illustrated in FIG.2. Each feeder is designed to accept several different types ofcomponents for assembling a wide range of circuits and products. Theloaded feeders 16 are then mounted in slots according to an arrangementprescribed by a placement program which is loaded into the placementmachine controller. The placement program contains, among other things,a prescribed association between machine slot numbers and component partnumbers.

In accordance with the invention, each feeder 16 has an associated barcode label 22 affixed to an exposed surface near the dispensing tip ofthe feeder. Label 22 contains sufficient information to identify theindividual feeder. As the feeder is loaded with a particular componentreel, which may be done with spare feeders in a stock room away from themachine to avoid excessive down time, the operator inputs the loadinginformation of the feeder. In other words, the operator associates inthe data base of the monitoring system the identification and quantityof the loaded component with the particular feeder upon which it isloaded. This data input is conveniently performed with a hand-held barcode scanner for reading labels 22 and scannable componentidentification labels (not shown) provided on reels 20 by the componentsuppliers. The Electronic Industries Association (EIA) has established astandard format for bar coding such reel labels, in which the bar codegraphic indicates, in order, the customer part number, the supplier partnumber, and the component quantity. Preferably, the EIA standard reellabels are scanned only once and a unique reel label is then assigned toeach reel to keep track of the quantity of components on each individualreel in cases where the original reel identification label does notinclude a reel-specific identification number. When the loaded reels 16are brought to machine 10 for loading into slots of the feeder platform18 (FIG. 1), the machine controller prompts the operator to place agiven component part number in a given slot based upon informationprovided in the placement program. The operator determines, typically bylooking at the reel identification labels on reels 20, which feeder 18contains the requested component and loads the feeder into the indicatedslot.

Referring to FIG. 3, the monitoring system of the invention includes, inthis embodiment, a feeder bar code label scanner 24a and a slot bar codelabel scanner 24b. Feeder platform 18 has a series of slot bar codelabels 26 affixed to its exposed lower surface in association withrespective slots 28 of the platform. Both scanners are mounted on thestationary portion of the placement machine, such that feeder platform18 moves back and forth with respect to them to present specific feedersto the pick/place mechanisms. Thus, the scanners do not move withrespect to the pick location. Scanner 24a is arranged to scan the label22' of the feeder 16' aligned at the pick location, and scanner 24b isarranged to scan the slot label 26' of the slot 28' in which the alignedfeeder 16' is mounted.

With reference also to the flow chart of FIG. 4, when triggered by thepicking of a component, scanner 24a scans label 22' to determine theidentification of feeder 16'. The picked component is identified by theassociation between feeder and component reel that was previously inputinto the system database when the feeder was loaded. Meanwhile, scanner24b scans slot label 26' to determine the slot number. Referring toinformation provided by the placement program, the monitoring systemdetermines the component number that is supposed to be loaded at slot28'. This component identification is compared to the componentidentification determined by the scanning of feeder label 22' by scanner24a. If the identifications do not match, an alarm sounds. Thus thesystem continuously monitors the arrangement of feeders 16 to detecterrors in feeder platform loading. If the identification numbers are thesame (i.e., the feeder number and slot number indicate the samecomponent identification) then the database is updated and the processrepeats upon the next pick. The updating of the database includesdecrementing the recorded quantity of components on feeder 16' forinventory control and updating the recorded number of times a particularfeeder has been accessed (or picked from) for feeder maintenancepurposes. If packaging constraints permit, a single bar code scanner maybe employed to scan both the feeder and slot labels.

The computational steps and alarms indicated on FIG. 4 are effected by apersonal computer 30 (FIG. 3) running software designed for thispurpose. The computer may be connected to the placement machinecontroller via RS232 or ethernet connection. Other hardware forimplementing the monitoring system on a single conventional placementmachine includes the scanners 24a and 24b and an additional handheldscanner (not shown) for inputting the feeder loading information as thefeeders are loaded with component reels.

In a multi-machine system illustrated in FIG. 5, the database is managedby a central server 32 connected to individual machine monitoringsystems 34 by an ethernet connection. Also connected for access to thedatabase are a loading station 36 and a tracking station 38. Loadingstation 36 includes a hand-held bar code scanner 39 for inputting feederloading information as component reels are loaded onto feeders for useon the various machines. Tracking station 38 contains software foraccessing database information to track the status of feeders and loadedinventory. Having a common database simplifies the tasks of jobsupervision and inventory management.

Accessing a common database shared by several machines each picking upto 30,000 components per hour can, however, require specialconsiderations. FIG. 6, for instance, illustrates how cache memorymanagement can be employed at each monitoring system for use withextremely fast placement machines and a common database. Before runningthe placement machine, the monitor system queries the database for allfeeder numbers associated with each of the component numbers listed inthe placement program and stores this list of feeder IDs in local memoryalong with the quantity of components known to remain in the feeder (thereel or component quantity). Cache memory is initially empty.

During each pick cycle, the monitor system scans the feeder label (forfeeder ID) and slot label (for slot number) at the pick location. If thescanned feeder ID is not found in cache memory, the system looks for thefeeder ID in local memory. If not in either memory location, an alarm isgenerated. If the feeder ID is found in local memory only, the feeder IDis added to cache memory. Cache memory can be thought of as a list ofthe feeders known to be present on the feeder platform of the machine.Local memory is a list of all feeders the common database associateswith the part numbers of the placement program. Therefore, as themachine runs, cache memory will be updated each time the monitor systemidentifies another feeder on the machine. After each pick, the systemincrements the feeder stroke count in cache memory (initially zero) anddecrements the reel quantity in cache memory. Local memory is notaltered once the list of feeders is initially entered from the database.If the component quantity indicates that the feeder is now empty (e.g.,that the feeder was replenished without properly scanning in thereplacement reel), or if an error is detected in the feeder arrangement(as explained above with reference to FIG. 4), an alarm is generated.Otherwise, the cycle is repeated. In each instance where an alarm issounded, the monitor system also stops the operation of the placementmachine via a switch in its emergency stop ("e-stop") circuit.

After a fixed number of machine strokes (pick cycles), or after apredetermined time interval, the common database is updated over theethernet connection. This update task is programmed to be performed as abackground task, such that the monitoring tasks associated with thealarms are given highest priority. The current implementation updatesthe database after every 2,000 picks or every 10 minutes, and theseintervals are adjustable by the user. During the update, the feederstroke count in the database is incremented by the feeder stroke countin cache memory and the cache feeder strokes are reset to zero. Thecomponent quantities associated with the feeders in the database arealso updated. Coincident with each database update, the cache memory ispurged of any feeders not accessed since the previous database update byclearing from cache memory all feeders with stroke counts that have notadvanced from zero. This may indicate, for instance, that a feeder hasbeen replaced.

Thus, about every ten minutes or so the common database is updated toreflect the current level of inventory on all feeders in all machines.In circumstances where a substantial portion of component inventory in aplant at any given time is in partially used reels on feeders, themonitoring system doubles as a valuable inventory management tool.

The invention is also applicable for use with component placementmachines in which the feeder platform remains stationary and the picklocation moves, as illustrated in FIG. 7. Machines of such configurationare generally employed for mounting larger components that require veryprecise location, such as processors. In this embodiment, a singlescanner 40 continuously scans associated pairs of slot labels and feederlabels as the translatable picking mechanism 42 moves back and forth,sending a stream of information to the monitoring system to check forerrors. As there is no indication to the monitoring system of whatfeeder is being picked from, this particular embodiment does not monitorfeeder inventory or stroke count.

The feeder bar code labels 22 can be made very small to fit on availableexposed surfaces of standard, commercially available feeders. FIG. 8shows an actual example of a feeder bar code label 22 developed for afirst implementation of the monitoring system. The feeder identificationnumber consists, in this example, of a three-digit alphanumericsequence. To help avoid confusion between similar characters, apreferred set of alphanumeric characters consists of the numbers 0-9 andthe letters A-Z without the letters O, Q, D, G, I, J, U or Z. Theresulting character set allows for over 22,000 unique combinations,sufficient to accommodate the number of individual feeders in use atmost manufacturing plants.

It is preferred that the feeder bar code labels 22 be placed on thefeeders as near as possible to the location of the feeder mount (i.e.,the most secure and stable portion of the feeder), in order to avoidissues related to vibrations induced in the feeder by rapid feederplatform accelerations.

Referring to FIG. 9, in another embodiment the component reels 20' aresupplied with duplicate, removable component bar code labels 44 of EIAstandard format. Labels 44 have an adhesive backing such that they maybe applied to the feeder upon which reel 20' is mounted, adjacent thefeeder bar code label. This configuration eliminates the need to enterfeeder loading information, as the monitor system can be adapted todirectly read component identification information simultaneously withfeeder identification. Each time a reel is mounted to a feeder, anotherlabel 44 is removed and affixed to the feeder, either over the label ofthe previously installed reel or after removing the old label. Enoughlabels 44 are provided on reel 20' to accommodate a reasonable number ofremountings.

Other embodiments and advantages also fall within the scope of thefollowing claims.

What is claimed is:
 1. An apparatus for monitoring a configuration ofcomponent feeders in a placement machine having a series of feeder slotsfor holding the component feeders, the apparatus comprisingslot markersfor installation on the placement machine to correspond to the feederslots; feeder markers for installation on the component feeders of theplacement machine; and a marker detector adapted to monitor thearrangement of slot markers and feeder markers in the machine byreferencing stored configuration data as the machine plates componentspicked from the feeders.
 2. The apparatus of claim 1 wherein the slotmarkers and feeder markers comprise light-scannable labels and themarker detector includes a scanner arranged to scan the slot markers andfeeder markers.
 3. The apparatus of claim 2 for use with a placementmachine that includes a moving picking mechanism and a stationary feederplatform, wherein the scanner is constructed to be attached to themoving picking mechanism of the placement machine.
 4. The apparatus ofclaim 2 for use with a placement machine that includes a rotatablepicking mechanism, a moving feeder platform and a stationary portion;wherein the scanner is constructed to be attached to the stationaryportion of the placement machine.
 5. The apparatus of claim 2 for usewith component reels with light-scannable labels, the apparatus furthercomprising a loading scanner adapted to scan the reel labels and feederlabels as the reels are mounted upon the feeders to identify whichcomponent is loaded on a given feeder.
 6. The apparatus of claim 1wherein the marker detector is arranged to substantially simultaneouslyscan the slot marker of a given slot and the feeder marker of the feederin the given slot.
 7. The apparatus of claim 6 adapted to be triggeredto scan a given slot marker and corresponding feeder marker by themachine as the machine picks a component from the slot corresponding tothe given slot marker.
 8. The apparatus of claim 1 wherein the markerdetector is adapted to compare the arrangement of slot markers andfeeder markers to stored data while the machine is placing components.9. The apparatus of claim 8 further comprising means to alert anoperator upon detection of an undesirable arrangement of slot markersand feeder markers.
 10. The apparatus of claim 1 further comprising adata storage device adapted to store component feeder configurationdata.
 11. The apparatus of claim 10 wherein the data storage device isadapted to record the number of components remaining in each componentfeeder.
 12. The apparatus of claim 10 wherein the data storage device isadapted to track the number of times a given component feeder has beenaccessed by the placement machine.
 13. The apparatus of claim 10 furthercomprising a data link between multiple placement machines and said datastorage device.
 14. The apparatus of claim 13 wherein the data storagedevice is adapted to update component feeder information from amultiplicity of placement machines.
 15. In a placement machine formounting electronic components on circuit boards, the machinecomprisinga series of feeder slots for holding component feeders; and apicking device constructed to pick components from the feeder slots formounting to a circuit board; the improvement wherein the placementmachine further comprises a system for monitoring the configuration ofthe component feeders in the feeder slots, the system comprisingslotmarkers for installation on the placement machine to correspond to thefeeder slots; feeder markers for installation on the component feedersof the placement machine; and means for monitoring the arrangement ofslot markers and feeder markers while the machine plates componentspicked from the feeders.
 16. A method for monitoring a configuration ofcomponent feeders in a placement machine having a series of feeder slotsfor holding the component feeders, the method comprisingscanning, whilethe machine is in process of picking components from given feeder slots,slot markers corresponding to the slots and feeder markers correspondingto the component feeders in the slots; and comparing configurationinformation gathered by said scanning with previously storedconfiguration information to check for configuration errors.
 17. Themethod of claim 16 wherein the steps of scanning and comparing areperformed while the machine is placing components.
 18. The method ofclaim 17 further comprising alerting an operator upon detection of anundesirable arrangement of slot markers and feeder markers.
 19. Themethod of claim 16 further comprising, prior to the operation of theplacement machine,installing component reels in feeders; scanning reellabels and feeder labels of their associated feeders to identify whichcomponents are loaded on which feeders; and mounting the loaded feederson the placement machine.